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| dp111443 |
 Posted: Mon Oct 25, 2004 7:06 am Post subject: MQ active logs |
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Voyager
Joined: 25 Feb 2004
Posts: 82
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Hi,
I have a quick question about active logging in MQ. We had an incident where by a /var/mqm/logs filesystem filled up. Help desk at my company didn't realise what the files were and deleted all of them on a sunday 3pm.
We then didn't find out that there was a problem till the next day at 5pm (after 26hrs).
According to apps people, data was still going through MQ as no customers reported a problem, but I don't understand how this could be if the file system was full and the active logs that MQ was using at the time was deleted. Is this possible? Does MQ use temporary logs somewhere else? or would it just carry on by creating another log??
The reason we found at after 26 hrs. is the box was rebooted. of course MQ coudn't find the media (MQ objects to recover) and complained that there are no logs to recover from. The qmgr had to be rebuilt.
If someone could explain this to me then that would be fab.
thanks
Dharmesh
_________________
Integration Design/Developer
IBM Certified System Administrator -
WebSphere MQ V5.3 |
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| vennela |
| Posted: Mon Oct 25, 2004 7:22 am Post subject: |
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Jedi Knight
Joined: 11 Aug 2002
Posts: 4055
Location: Hyderabad, India
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| Quote: |
| According to apps people, data was still going through MQ |
No way
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| Is this possible? Does MQ use temporary logs somewhere else? |
NO |
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| dp111443 |
| Posted: Mon Oct 25, 2004 8:00 am Post subject: |
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Voyager
Joined: 25 Feb 2004
Posts: 82
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Just as I thought then.
thanks for confirming!
_________________
Integration Design/Developer
IBM Certified System Administrator -
WebSphere MQ V5.3 |
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| PeterPotkay |
| Posted: Mon Oct 25, 2004 8:59 am Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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If the type of messaging is soley NP messages outside of syncpoint, is it not possible that messaging could continue for a while, as the QM doesn't need to write to the logs in this scenario?
http://www.mqseries.net/phpBB2/viewtopic.php?p=76185#76185
This is an explanation of how logs and disk come into play that I got from IBM.
Seems to me that messages could go thru without logs if conditions were right. I don't know how long it would be before the QM required the logs for other reasons, at which point it would stop?
_________________
Peter Potkay
Keep Calm and MQ On |
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| mrlinux |
| Posted: Mon Oct 25, 2004 9:20 am Post subject: |
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Grand Master
Joined: 14 Feb 2002
Posts: 1261
Location: Detroit,MI USA
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Were all the logs deleted, depending on the platform you cant delete the active log file, but all the rest will be deleted and if you try to restart MQ it will notice the logs missing. This also assumes the current log doesnt need to be swicthed to a new one.
_________________
Jeff
IBM Certified Developer MQSeries
IBM Certified Specialist MQSeries
IBM Certified Solutions Expert MQSeries |
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| sjensen |
| Posted: Wed Oct 27, 2004 4:40 am Post subject: |
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Centurion
Joined: 18 Dec 2003
Posts: 134
Location: London
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| Quote: |
| According to apps people, data was still going through MQ |
This is possible at least on Solaris and I suspect on other flavours of Unix as well. The active logfile will appear to be deleted but will still exist 'under the covers' until it is closed. Hence if the deletion created some free space it is quite likely messages would still flow.
I just tested this, I removed all the logfiles for my Queue Manager and send messages to both local and remote queues. Of course once the file is closed starting the Queue Manager again will be a problem.
In my opinion this is actually worse than if WMQ would just crash at least that way you find out quicker than somebody has deleted all the logfiles.
Cheers
Stefan |
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